Photo by Associated Press The Nationals' Ryan Zimmerman follows through on a two-run home run during the fifth inning of a baseball game against the Florida Marlins on Thursday. The Nats won 12-8.

Ryan Zimmerman finished a double short of the cycle, and Ronnie Belliard's tiebreaking single in the eighth inning helped Washington rally from a six-run deficit and beat the Florida Marlins 12-8 on Thursday.

The Nationals broke an 8-all tie with four runs in the eighth, completing a series sweep and winning their season-best fifth straight game. Jorge Sosa (1-0) got out of an eighth-inning jam and pitched the ninth to earn the win.

Washington also scored six runs in the eighth inning for a 6-4 victory on Tuesday, and have come from behind for 20 of its major-league low 37 wins.

"Nobody in that room has any doubts they can come back," said interim manager Jim Riggleman. "The feeling is that it's six runs, but it's early, and if we just get a couple and now, all of a sudden, maybe get that other club thinking 'Well, here they come again.'"

Zimmerman continued his recent hot streak with two singles, a triple, a homer and three RBIs. He also walked to reach base in all five plate appearances, and is hitting .449 in his last 13 games.

"We've been playing good baseball," Zimmerman said. "We don't ever think we're out of it, and we want to do that for the rest of the season."

They did it after Florida took early leads of 6-0 and 8-3, which the Marlins built on three hits in the first five innings by Hanley Ramirez and John Baker's two-run homer.

Alberto Gonzalez sparked Washington with a two-run double in the fourth, and Zimmerman added a two-run shot in the fifth as the Nationals cut the lead to 8-7. Dukes, who had three hits and drove in four runs, then tied it with a solo homer in the seventh off Brian Sanches.

Cristian Guzman started the go-ahead rally with a leadoff walk, and Nyjer Morgan sacrificed him to second before Belliard singled to center off Luis Ayala (1-4) for a 9-8 lead. Zimmerman added an RBI triple to give Washington a 10-8 edge. Dukes hit an RBI single, and the Nationals scored another run on Brendan Donnelly's balk.

"We just keep coming back and winning some games," Belliard said. "Winning five in a row -- it feels good."

Belliard had a pair of hits and scored twice for the Nationals. Josh Bard also drove in a run.

Washington starter Craig Stammen lasted just 1 2-3 innings, and Riggleman used seven pitchers. Riggleman had said before the game that he wouldn't use Mike MacDougal as the closer after he pitched four straight days.

Stammen's early exit forced Riggleman to go to the bullpen often, and the six relievers combined to give up just two runs on five hits in 7 1-3 innings.

The Nationals also came up with the timely hits that the Marlins couldn't. Washington went 7 for 12 with runners in scoring position.

"They did a great job of swinging. They're playing really well right now," said Florida starter Chris Volstad. "We've got to put this series behind us. That's really all you can do."

NOTES: Zimmerman extended his hitting streak to 10 games... This was just the second time since the Nationals came to Washington that they overcame a six-run deficit to win. The other time came on June 17, 2006 against the Yankees... Baker's homer was his first since July 3. ... Marlins starter Josh Johnson made his first career pinch-hitting appearance, drawing a walk in the sixth. Johnson homered in Tuesday's 6-4 loss to Washington.